package cn.texous.util.commons.util.copy;

import java.io.InputStream;

/**
 * ByteArrayInputStream implementation that does not synchronize methods.
 */
public class FastByteArrayInputStream extends InputStream {
    /**
     * Our byte buffer
     */
    protected byte[] buf = null;

    /**
     * Number of bytes that we can read from the buffer
     */
    protected int count = 0;

    /**
     * Number of bytes that have been read from the buffer
     */
    protected int pos = 0;

    public FastByteArrayInputStream(byte[] buf, int count) {
        this.buf = buf;
        this.count = count;
    }

    public final int available() {
        return count - pos;
    }

    public final int read() {
        return (pos < count) ? (buf[pos++] & 0xff) : -1;
    }

    /**
     *
     */
    public final int read(byte[] b, int off, int len) {
        int length = len;
        if (pos >= count)
            return -1;

        if ((pos + length) > count)
            length = count - pos;

        System.arraycopy(buf, pos, b, off, length);
        pos += length;
        return length;
    }

    /**
     *
     */
    public final long skip(long n) {
        long sk = n;
        if ((pos + sk) > count)
            sk = count - pos;
        if (sk < 0)
            return 0;
        pos += sk;
        return sk;
    }

}
